This invention relates to synthetic vascular grafts, and more particularly to synthetic vascular grafts having an integrally formed flange on at least one end to facilitate end-to-side anastomoses.
Vascular grafts of synthetic materials are widely used for the replacements of segments of human blood vessels. Synthetic vascular grafts have taken a wide variety of configurations and are formed of a wide variety of materials. Among the accepted and successful vascular graft implants are those which are formed from a biologically compatible material which retains an open lumen to permit blood to flow through the graft after implantation. The biologically compatible materials include polyester, polytetrafluoroethylene (PTFE), silicone and polyurethanes. The most widely used are polyester fibers and PTFE. The polyester fibers (usually Dacron) may be knitted or woven and may be of a monofilament, multifilament or staple yarn.
There are a wide variety of synthetic vascular grafts presently in use. An important factor in the selection of a particular graft substrate is the porosity of the substrate of which the graft is formed and the strength requirements. Porosity of the graft is significant because it controls the tendency to hemorrhage during and after implantation and influences ingrowth of tissue into the wall of the graft. Synthetic fabric vascular grafts may be of a woven, knit or velour construction. A warp-knit graft is disclosed in U.S. Pat. No. 3,945,052 and a warp knit double-velour construction is disclosed in U.S. Pat. No. 4,047,252. A synthetic woven double-velour substrate is described in U.S. Pat. No. 4,517,687.
These issued United States patents for synthetic vascular grafts are assigned to the assignee of this application. After knitting or weaving the grafts are compacted and then crimped to provide the crimping which facilitates maintaining the open lumen during flexing of the graft. Methods of compacting are shown in U.S. Pat. Nos. 3,853,462 and 3,986,828.
Most operations requiring transection of a vessel involve end-to-end anastomoses. However, there is a large number of end-to-side anastomoses. Simple or bleak transection of a graft to be used for an end-to-side anastomoses may tend to create a short zone of arterial constriction at the apex of the graft unless extreme care is used in the placement of the graft and sutures during implant.
It has been a known and useful technique for anastomosing a tubular fabric graft to the side of the aorta when a small graft is necessary to match the size of the artery to which it is to be connected distally. If for example, an aorta-to-celiac graft requiring a 6-mm graft is appropriate, the graft can be cut from a 12.times.6 bifurcation preserving a flange from its aortic segment. This flange has allowed for rapid placement of the sutures in the aortic wall without the risk of serious narrowing of the stoma.
An example of this technique is shown in FIG. 1 wherein a bifurcated polyester fiber graft 11 having a main body segment 12 and two legs 13 and 14. Legs 13 and 14 are joined to main body 12 at a crotch 15 which is usually reinforced by a row of stitches 17 to maintain as tight an initial porosity of the graft as possible and maintain its integrity during handling after weaving or knitting. Stitches 17 are necessary to close the space in crotch 16 between legs 13 and 14 which forms during knitting or weaving. Graft 11 is formed of a polyester fiber, either knit or woven, compacted and given a series of circular crimps 16 about main body 12 and legs 13 and 14.
In order to use graft 11 for an end-to-side anastomoses, graft 11 has been cut along a line 18. This provides a flanged graft 21 as shown in FIG. 2 having a straight portion 22 with an integrally formed flange portion 23. An illustration of placement of graft 21 along an artery wall 24 and secured by sutures 26 is shown in FIG. 3.
While this technique has been followed for some time with success, the results are not entirely satisfactory and it is desirable to provide a flanged end-to-side vascular graft of improved construction. The difficulty with graft 21 is that the graft is harvested from bifurcated graft with crotch 16 reinforced with stitches 17. The reinforcement is hard and tends to cause crotch 16 to curve towards back toward straight portion 22 and makes it difficult to suture. Stitches 17 cause breaks or bends in suturing needles which can tend to tear the artery when end-to-side graft 21 is being attached. Efforts at avoiding this difficulty by cutting crotch wider has not been successful and the problems noted above continue to plague the vascular surgeon.
Accordingly, it is desirable to provide an improved synthetic flanged end-to-side vascular graft including an integral flange which avoids the difficulties present in the prior art.